But for those affected by the "unethical, immoral and illegal" act, the Premier apologised.

"Mothers have told us of their experiences of being drugged during labour, of pain medication being withheld as a punishment for being unmarried," Ms Giddings said.

"Some of you had your faces covered with pillows as you have birth.

"To you, the mothers who have suffered so much, we acknowledge your anger and your grief and your deep, deep loss and we are sorry.

"To the children, who are now grown up, and who have lived lives full of questions without answers we recognise you have suffered profound feelings of abandonment and loss, and have struggled with issues of identity.

"To you, those children who are now adults, we acknowledge you trauma and your loss, and we are sorry."

Tasmania's Parliament is the fourth in Australia to apologise to those affected by forced adoptions.